Computing devices, such as mobile phones, tablet devices, laptop computers and any other communication-enabled devices wirelessly communicate with access points, such as implemented in a Wi-Fi network. A mobile computing device is commonly referred to as a client device or “station” in a Wi-Fi network. Generally, a station may be any portable, mobile, or fixed computing device designed to be IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi) compliant with a media access control (MAC) and physical layer (PHY) interface for wireless communication. A station communicates with an access point that is within communication range in the Wi-Fi network.
Generally, an access point, such as may be implemented in a router device, provides network connectivity for a Wi-Fi compliant device, such as a fixed or mobile computing device. Additionally, access points typically have a greater communication range than do the stations, which may vary in power-level capabilities, some being high-end stations with more of a communication range and others being low-end stations with less of a communication range. However, all of the stations need to be able to associate and communicate with an access point to enable wireless communication on the Wi-Fi network.
Often, a station can receive a beacon and downlink packet from an access point in the network, but cannot associate and exchange data frames with the access point due to a limited communication range of the station. Due to the asymmetric uplink/downlink budget for packet exchange between an access point and a low-end station, an uplink single-user (UL-SU) packet from a station device may not reach the access point even though the station receives a downlink packet from the access point. For example, an access point may be designed to support uplink OFDMA (Orthogonal Frequency-Division Multiple Access) including random access uplink OFDMA, such as proposed in the new IEEE 802.11ax protocol.
With this digital modulation technique, multiple stations can communicate with an access point by assignment of subsets of subcarriers to individual ones of the stations, which provides for simultaneous low data rate transmission from several stations. If the access point supports uplink OFDMA and the station transmits an association request or other request frames through the uplink OFDMA via the resource unit designated for random access, a particular station may not yet have an association identifier (AID) to participate in downlink OFDMA and receive the corresponding response, even though the access point can use EDCA (Enhanced Distributed Channel Access) single-user (SU) to deliver such a response. Further, an acknowledgement (ACK) from the station may not reach the access point due to the low power and limited communication range of the station.